Security screens are known in the art, but generally these screens are constructed so as to be substantially heavy, whereby opening or closing of the screens involves movement of a great amount of weight. This is often because the screens are constructed to be of the parallel linkage type, with the angularly moveable links that connect vertical bars in general traversing a plurality of such bars. Typical of the parallel linkage type of screen or gate is that disclosed in the patent to Coomes, U.S. Pat. No. 917,713.
Other foldable structures, principally of the gate type have been developed, that do not employ links that traverse a plurality of parallel vertical bars, but this type employs vertically moveable intermediate bars between the principal vertical bars, and in order to provide for such vertical movement, substantial unsecured areas exist above and below the area of principal screening when such screens or gates are in use. Typical of this type of gate is that shown in the patent to Jackson, U.S. Pat. No. 1,721,998.
The prior art directed to collapsible screeens or gates is apparently one that has developed at a time when customized design was possible for almost each installation.